1. Field of the Invention
The invention relates to power amplifiers, and more particularly to radio frequency (RF) power amplifiers.
2. Description of the Related Art
The rapid development of E-band and W-band communications, radar, and imaging systems, has been facilitated by the use of power amplifier cell arrays developed using indium phosphide (InP) and silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies achieving high current and low voltage solutions. A gallium nitride (GaN) high electron mobility transistor (HEMT) power amplifier cell (high voltage, low current technology) for use in such arrays may utilize thru-substrate reactive microstrip for power combining with adjacent cells. The RF matching networks may share the same RF matching structure as that used for DC current in such arrays.
Unfortunately, as such topologies are used for ever-higher frequency and output power applications, usable bandwidth in such power amplifier cell arrays tends to decrease. A need continues to exist to provide for high frequency and high power RF power amplifiers while maintaining or extending usable bandwidth.